Abstract: A sealing member 10 for a valve 12 includes a body 14 defining a cavity 16 and, a resiliently deformable membrane 18 extending across a lower end 20 of the body 14. The membrane 18 is provided with an aperture 22 through which fluid can flow to enter the cavity 16. The valve 12 typically has an inlet 24, an outlet 26, and a seat 28 through which fluid must flow in order to pass from the inlet 24 to the outlet 26. The sealing member 10 is configured to seal against the seat 28. When the sealing member 10 is seated on seat 28 to at least partially seal the valve 12, fluid enters the cavity 16 through aperture 22 and, by action of fluid pressure in the fluid, forces the resiliently deformable membrane 18 against the valve seat 28 to further seal the valve 12.